Angioplastic techniques for creating and enlarging openings in obstructed or partially obstructed blood vessels by inflating a balloon or another device at or near the site of an occlusion using an interventional catheter are well known and commonly employed. Material forming the obstruction is typically compressed during angioplasty as the vessel wall is stretched to enlarge the vessel lumen. An implantable device, such as a stent, may be placed at the site to maintain or improve vessel patency. Restenosis of vessels following angioplasty and stent placement procedures is common and may require additional interventions. Drug-eluting stents were developed to retard or reduce the incidence and severity of restenosis and have been effective in many circumstances.
Removal of diseased tissue, such as atherosclerotic plaque, thrombus and other types of obstructions and partial obstructions from internal body lumens or cavities is also a well-established interventional technique. Numerous interventional catheters have been conceived and developed. Most of these systems require placement of a guiding catheter and guide wire prior to introduction of the interventional catheter and placement of the interventional catheter near the target operating site. Advanceable, rotating operating heads have been used to cut and/or abrade and/or ablate obstructions. Plaque excision devices that incorporate cutting or scraping structures operating through a window or port, or having coring or helical screw structures that operate in a recessed opening, are also used. Aspirating catheters have been used to remove diffuse material, such as thrombus. Many of these prior art systems incorporate aspiration or mechanical withdrawal systems to remove the obstructive material from the site. Some systems incorporate or are used in conjunction with mechanisms such as distal filters for preventing obstructive material from circulating in the blood stream.
Other types of material removal systems, such as excimer lasers, high intensity focused ultrasound systems, RF systems, and the like have also been devised and used. Although mechanical devices such as cutter-based and mechanical removal devices and laser and ultrasound-based systems are effective in removing diseased tissue from and opening lumens through blood vessels, it is difficult to prevent restenosis of the vessel following material removal. Thus, despite the many and varied techniques used to prevent blood vessels from becoming occluded and the successful removal of material and placement of implantable devices such as stents, prevention of restenosis following the intervention remains problematic.
Many interventional devices have infusion systems that infuse liquids such as saline, imaging compositions, or therapeutic and/or diagnostic compositions to a site of intervention prior to or during operation of the device. Delivery of therapeutic and/or diagnostic compositions in solution using conventional infusion protocols generally isn't effective for treatment of tissue at interventional sites in blood vessels because the infusate is rapidly diluted and carried away in the bloodstream. For effective therapy or diagnosis, the composition must generally remain in contact with and have an opportunity to interact with the diseased or affected tissue. Delivery of therapeutic and diagnostic compositions to interventional sites in the blood stream thus remains challenging.
Many systems have been conceived and developed for delivery of therapeutic compositions to an interventional site. U.S. Patent Publication No. US 2005/0250672 describes a composition for restenosis prevention including an antihyperplastic composition. The composition may be applied to the outer surface of a catheter for delivery. U.S. Patent Publication No. US 2006/0020243 discloses balloon catheters coated with lipophilic drugs. U.S. Pat. No. 6,939,320 discloses a medical device including an expandable substrate, such as a balloon catheter, coated with a drug, and an expandable sheath positioned over the substrate, the expandable sheath having at least one perforation that is substantially closed when the substrate and the sheath are in a compressed state and substantially open when the substrate and sheath are expanded. The drug is thus able to pass through the sheath following expansion of the substrate and sheath.
U.S. Pat. No. 6,997,898 discloses a catheter provided with multiple inflatable balloons that, when inflated, create closed delivery pockets for delivery of compositions to a defined space. PCT International Publication No. WO 2005/055800 provides a method for exposing the luminal wall of a blood vessel to a substance by deploying a drug-eluting polymer film inside the lumen of the blood vessel during or following angioplasty.
U.S. Pat. No. 5,843,033 discloses an inflatable balloon catheter having a plurality of conduits in fluid communication with a plurality of apertures on the outer surface of the balloon, whereby medications are transferred from the conduits into a surrounding vessel following inflation of the balloon. U.S. Pat. No. 6,210,392 provides a device including an inflatable balloon mounted on a catheter, the balloon having a plurality of dispensers that extend outwardly from the balloon and are in fluid communication with a fluid source. Following delivery of the balloon to a treatment area in a vessel, the balloon is inflated to embed the dispensers in the vessel wall and fluid is introduced into the treatment area. U.S. Patent Publication No. US 2004/0098014 discloses a balloon angioplasty device having a plurality of cutting elements, such as microneedles, provided on the outer surface of the balloon. The microneedles enhance dilation of an artery and may be employed to deliver a drug to a cutting region.
U.S. Pat. No. 5,196,024 discloses a balloon catheter having cutting edges located parallel to the longitudinal axis of the balloon that make longitudinal cuts in a vessel wall. During delivery, the cutting edges are covered by folds of the deflated balloon, thereby minimizing injury to the vessel wall. U.S. Pat. No. 5,320,634 describes an angioplasty device comprising an inflatable balloon having a plurality of atherotomes mounted on its outer surface, the balloon being mounted on a catheter.